1. Field of the Disclosure
The present invention relates generally to power supplies, and more specifically, the invention relates to reducing the input current harmonics of a power supply.
2. Background
Power supplies are typically used to convert alternating current (“AC”) power provided by an electrical outlet into usable direct current (“DC”)power for an electrical device. One important consideration for power supply design is the power quality, or in other words the efficiency with which power is delivered to the power supply. More specifically, power quality may be quantified by a power factor, which is a ratio of the amount of usable power delivered to the power supply divided by total power delivered to the power supply. Usable power may be defined as power that is used by the load coupled to the output of the power supply. Total power is the sum of usable and unusable power delivered to the power supply. Unusable power may be defined as power that is delivered to the load but not used by the load and returned back to the input of the power supply.
During power supply operation, it is beneficial to have a high power factor (majority of total power is usable power) to increase efficiency. Unusable power delivered causes an additional dissipation of power due to an increased current when transferring power through the power supply. Additionally, electrical components in the power supply may need to be designed to receive the higher currents to deliver the same amount of power to the load which may increase cost and size of the power supply.
One aspect that contributes to additional unusable power is distortions in the current and/or voltage waveform delivered by the power distribution system. Typically, these distortions of current and/or voltage may be the result of electromagnetic interference coupled during transmission of power through the distribution lines. In order to design efficient power supplies it is important to increase power quality of the incoming power into the power supply. A common method to increase power quality of incoming power to the power supply is to use a boost converter to transform the current waveform back to its ideal sinusoidal shape.